Magnetic storage devices remain a viable solution for the storage and retrieval of large amounts of data. The use of magnetic tape cartridges, e.g., such as half-inch digital linear tape (“DLT”), linear tape open (“LTO”) and helical scan tapes formats, such as 4 mm (“DAT”, “8 mm”) are well known in the art. Tape cartridges can store a vast amount of data. Tape drives can be used either singly as stand alone tape drive or in a tape library (also referred to as a media library).
Generally, each tape drive includes multiple recording and reproducing transducers to write and/or read data to the tape cartridges. Typical modern tape drives use thin film magnetoresistive (MR) head or ferrite core transducers to read and/or writes data to the tape cartridges and are commonly referred to as tape heads. Magnetic storage devices are generally read/write capable and may be erased and written over many times during their lifetime.
For proper operation of the tape drive and to be able to record and reproduce data from the tape with acceptable data errors, the head must maintain very close proximity to the storage tape of the tape cartridge in order to provide the ability to record and reproduce signals. The head operates in an open environment and can be exposed to various contaminants from the open air and/or from the storage tape itself. Today's heads require very low separation between the head and the storage tape for greater accuracy in reading and writing of data. Excessive separation between the head and the storage tape and/or sensor damage such as scratches, nicks or other abrasions to the head itself can result in reading and writing errors or even head failure.
It is well known that tape to head separation increases when contaminants build up on the surface of the head. Cleaning cartridges or brushes can be used to remove contaminants. Unfortunately, these types of cleaning devices can be relatively ineffective for removing hardened deposits on the head. Further, when the sensor of the head is impacted with sufficient force, or when a conductive material causes a short in an element in the head, the head is rendered unusable and the drive must be repaired. In addition, contaminants and tape abrasive materials can generate surface scratches that effectively create permanent separation between the tape and the sensor. These defects will also reduce the head signal, requiring repair to the head.
Tapes are made of flexible basefilm such as PEN, PET or Poly-Aramid. The basefilm is coated with a very thin magnetic recording layer where the data is recorded. It is also well known that during normal operations, tapes degrade and lose their recording properties with repeated use of the same tape due to surface scratches caused by the running of the tape at close contact with the head. Furthermore, airborne contaminants deposited on the tape can cause tape surface damage such as scratches, nicks or other abrasions. Deposits, contaminants, or abrasions on the tape surface can result in reading and writing errors or even drive failure.
Presently, the drive diagnosis is lengthy, complex and costly. For example, when a tape drive fails within a media library, it is not possible to determine with certainty if the cause of the failure is marginal head or tape as both can produce data errors. In the case where multiple drives record data on the same cartridge, then it is virtually impossible to determine the marginal drive that caused the error, especially when the failure is compounded by a combination of the marginal heads and marginal media. Therefore, measuring the drive error rate is not a reliable method in identifying the marginal defective head.
The current practice in the tape industry is to ship the suspect drives back to the factory for extensive testing where the drives are disassembled and the suspect heads are carefully removed from the drives. Suspect heads are returned to the head vendors for test and possible repair. The head repair procedure can be proprietary to each head vendor, further complicating the entire head test process. Typically, nearly half of the drives returned by customers with suspected failure are found to have no problem and the failure was likely caused by marginal or defective media in the field. The current process consists of a complete and costly retest at the factory without the need for actual repair, the drive is returned so that it can be reinstalled for the customer.
Accordingly, methods and systems to determine with certainty the cause of data failures in the field, as caused by marginal head or media, and the need to eliminate the requirement for the costly and extensive factory diagnosis and associated head removals and tests, are highly desired.